[{"data":1,"prerenderedAt":2491},["ShallowReactive",2],{"$fuK9YpFu7S-qQnzo336n6C5zjWNriAB4iTtK3MiWVB0Q":3,"$fMMUdSFktwQFqMVGPrTtt3EC5yheBp7PzwIqznamFcMo":187,"$fc0LoAJgqXDLbKKd2JS_NpM4SuzBK8EycUXINSg09CKU":190,"$fM3ea55k6lKMPOTM84llDB26VSQDVVbxiQuSBFQw9P_c":195,"$f1Prj1xEczHja_-L7FyIGgRHd5_cSWHo7r6AE5aheAik":540,"$fI5fDmvm-5tr9wcH0eHaKZa1j3y_FQIQaHHPqbZxAHJE":762,"mdc--ap77t0-key":782,"mdc-ayajfc-key":794,"mdc--byvgp5-key":807,"mdc-oqyqr5-key":819,"mdc-y5uoas-key":831,"mdc-suhwcv-key":844,"mdc--whb1h4-key":856,"mdc--4rs9nt-key":868,"mdc-zg4gnw-key":881,"mdc-7qds4-key":912,"mdc-7dtsfb-key":1044,"mdc--2838bl-key":1060,"mdc-ehg4o1-key":1118,"mdc-id20pg-key":1134,"mdc-ju4lvg-key":1540,"mdc--a1jmyv-key":1589,"mdc-b4lip2-key":1609,"mdc--8kvgql-key":1622,"mdc-kjw5gr-key":1693,"mdc-9bb8p2-key":1741,"mdc--wy13pc-key":1758,"mdc--yb0duq-key":1771,"mdc-fniex-key":1844,"mdc-xde1k8-key":1905,"mdc-djyifl-key":1927,"mdc-j3xf0m-key":1940,"mdc--ogzwwp-key":1981,"mdc--8jum7a-key":1998,"mdc--di1zto-key":2060,"mdc-aig9a0-key":2115,"mdc-jf9aqz-key":2190,"mdc--enljkg-key":2229,"mdc--ezd53l-key":2237,"mdc-sck3e5-key":2250,"mdc-xzo0a3-key":2356,"mdc-4fylxs-key":2443,"mdc-opbv0n-key":2455,"mdc--swlwsn-key":2467,"mdc--vd7lr-key":2479},{"content":4,"quizQuestionContent":137,"type":176,"pageMeta":177},[5,9,13,16,20,24,27,31,34,38,41,44,47,50,53,56,59,62,65,68,71,74,77,80,83,86,89,92,95,98,101,104,107,111,114,118,121,124,127,131,134],{"id":6,"value":7,"isTypeH1":8},"1907","Какие типы данных существует в JavaScript?",true,{"id":10,"value":11,"anchor":12,"isTypeH2":8},"4375","Теория: какие типы данных есть в JavaScript","theory-js-data-types",{"id":14,"value":15,"isTypeParagraph":8},"10068","В спецификации ECMAScript значения делятся на примитивные типы и тип `object`. Примитивы представляют собой неделимые значения (число, строка и т.д.), а объекты — контейнеры со свойствами и поведением.",{"id":17,"description":18,"titleAlert":19,"isTypeAlertInfo":8},"641","Термин “тип данных” в JavaScript обычно означает именно эти 8 категорий значений: `undefined`, `null`, `boolean`, `number`, `bigint`, `string`, `symbol`, `object`.",null,{"id":21,"value":22,"anchor":23,"isTypeH2":8},"4376","Схема: примитивы и объекты","diagram-primitives-vs-objects",{"id":25,"value":26,"isTypeParagraph":8},"10069","```\nЗначения JavaScript\n├─ Примитивы (7)\n│ ├─ undefined\n│ ├─ null\n│ ├─ boolean\n│ ├─ number\n│ ├─ bigint\n│ ├─ string\n│ └─ symbol\n└─ Object (1, непримитивный)\n ├─ plain object {}\n ├─ array []\n ├─ function () {}\n ├─ date new Date()\n ├─ map/set new Map(), new Set()\n └─ и другие встроенные/пользовательские объекты\n```",{"id":28,"value":29,"anchor":30,"isTypeH2":8},"4377","Короткая таблица: тип, typeof, пример","table-typeof-examples",{"id":32,"value":33,"isTypeParagraph":8},"10070","| Тип | Результат `typeof` | Пример значения | Важная особенность |\n|---|---|---|---|\n| `undefined` | `undefined` | `undefined` | “Значение отсутствует” (часто у неинициализированных переменных) |\n| `null` | `object` | `null` | Историческая особенность: `typeof null` возвращает `object` |\n| `boolean` | `boolean` | `true` | Только `true` и `false` |\n| `number` | `number` | `42`, `3.14`, `NaN` | Все обычные числа, включая `NaN`, `Infinity`, `-0` |\n| `bigint` | `bigint` | `9007199254740993n` | Целые числа произвольной длины, литерал с `n` |\n| `string` | `string` | `\"привет\"` | Строки в Unicode, отдельного `char` нет |\n| `symbol` | `symbol` | `Symbol(\"id\")` | Уникальные идентификаторы, часто для “скрытых” ключей |\n| `object` | `object` (или `function`) | `{}`, `[]`, `() => {}` | Объекты и функции (функции — вызываемые объекты) |",{"id":35,"value":36,"anchor":37,"isTypeH2":8},"4378","Разбор каждого типа с примерами","each-type-explained",{"id":39,"value":40,"anchor":40,"isTypeH3":8},"4390","undefined",{"id":42,"value":43,"isTypeParagraph":8},"10071","`undefined` означает, что значение не задано. Часто появляется у объявленной, но не инициализированной переменной, у отсутствующего свойства, а также как результат функции без `return`.\n\nПримеры: `let a;` и `typeof a`.\n\n```\nlet a;\nconsole.log(a); // undefined\nconsole.log(typeof a); // \"undefined\"\n\nconst obj = {};\nconsole.log(obj.missing); // undefined\n\nfunction f() {}\nconsole.log(f()); // undefined\n```\n",{"id":45,"description":46,"titleAlert":19,"isTypeAlertWarning":8},"699","`undefined` и “не существует” — не одно и то же: переменная может не существовать (ReferenceError), а может существовать и быть равной `undefined`.",{"id":48,"value":49,"isTypeParagraph":8},"10072","```\n// Пример различия (в модуле/строгом режиме будет ReferenceError)\nconsole.log(notDeclared); // ReferenceError: notDeclared is not defined\n\nlet declared;\nconsole.log(declared); // undefined\n```\n",{"id":51,"value":52,"anchor":52,"isTypeH3":8},"4391","null",{"id":54,"value":55,"isTypeParagraph":8},"10073","`null` обычно означает “пустое значение по намерению”: объект отсутствует, ссылка очищена и т.п.\n\nПримеры: `const x = null;` и `x === null`.\n\n```\nconst x = null;\nconsole.log(x); // null\nconsole.log(x === null); // true\nconsole.log(typeof x); // \"object\" (историческая особенность)\n```\n\nПрактическая проверка на “null или undefined” часто делается через `x == null`, потому что нестрогое равенство в этом месте намеренно устроено так, что `null == undefined` истинно.\n\n```\nconst a = null;\nconst b = undefined;\n\nconsole.log(a == null); // true\nconsole.log(b == null); // true\nconsole.log(a === null); // true\nconsole.log(b === null); // false\n```",{"id":57,"value":58,"anchor":58,"isTypeH3":8},"4392","boolean",{"id":60,"value":61,"isTypeParagraph":8},"10074","`boolean` содержит только два значения: `true` и `false`. В условиях выполняется приведение к булеву значению (truthy/falsy).\n\nПример: `Boolean(\"x\")`.\n\n```\nconsole.log(typeof true); // \"boolean\"\nconsole.log(Boolean(0)); // false\nconsole.log(Boolean(\"\")); // false\nconsole.log(Boolean(\"text\")); // true\nconsole.log(Boolean([])); // true\nconsole.log(Boolean({})); // true\n```",{"id":63,"description":64,"titleAlert":19,"isTypeAlertWarning":8},"700","Объект-обертка `new Boolean(false)` является объектом и ведет себя как truthy в условиях, что часто вызывает ошибки.",{"id":66,"value":67,"isTypeParagraph":8},"10075","```\nconst b = new Boolean(false);\n\nconsole.log(typeof b); // \"object\"\nif (b) {\n console.log(\"Сработает, потому что это объект\"); \n}\n```",{"id":69,"value":70,"anchor":70,"isTypeH3":8},"4393","number",{"id":72,"value":73,"isTypeParagraph":8},"10076","`number` — единственный “обычный” числовой тип: целые и дробные значения, а также специальные значения `NaN`, `Infinity`, `-Infinity`. В основе лежит формат IEEE 754 двойной точности, что объясняет ошибки округления.\n\nПримеры: `Number.isNaN(NaN)` и `0.1 + 0.2`.\n\n```\nconsole.log(typeof 123); // \"number\"\nconsole.log(typeof 3.14); // \"number\"\n\nconsole.log(0.1 + 0.2); // 0.30000000000000004\nconsole.log(Number.isNaN(NaN)); // true\nconsole.log(NaN === NaN); // false\n\nconsole.log(1 / 0); // Infinity\nconsole.log(-1 / 0); // -Infinity\nconsole.log(Object.is(-0, 0)); // false (в JS существуют +0 и -0)\n```\n\nДля денежных расчетов часто выбирается подход “хранить в целых минимальных единицах” (например, копейки) или использовать `bigint` там, где нужна целочисленная точность и нет дробной части.",{"id":75,"value":76,"anchor":76,"isTypeH3":8},"4394","bigint",{"id":78,"value":79,"isTypeParagraph":8},"10077","`bigint` предназначен для целых чисел произвольной длины. Литералы пишутся с суффиксом `n`. `bigint` не смешивается с `number` в арифметике без явного преобразования.\n\nПримеры: `9007199254740993n` и `typeof 1n`.\n\n```\nconst safeLimit = Number.MAX_SAFE_INTEGER; // 9007199254740991\nconsole.log(safeLimit + 1); // 9007199254740992\nconsole.log(safeLimit + 2); // 9007199254740992 (теряется точность)\n\nconst big = 9007199254740993n;\nconsole.log(big + 2n); // 9007199254740995n\nconsole.log(typeof big); // \"bigint\"\n```\n",{"id":81,"description":82,"titleAlert":19,"isTypeAlertWarning":8},"701","Операции между `number` и `bigint` выбрасывают ошибку TypeError.",{"id":84,"value":85,"isTypeParagraph":8},"10078","```\nconst a = 10n;\nconst b = 2;\n\n// console.log(a + b); // TypeError: Cannot mix BigInt and other types\n\nconsole.log(a + BigInt(b)); // 12n\nconsole.log(Number(a) + b); // 12 (возможна потеря точности при больших значениях)\n```",{"id":87,"value":88,"anchor":88,"isTypeH3":8},"4395","string",{"id":90,"value":91,"isTypeParagraph":8},"10079","`string` хранит текст. Отдельного типа “символ” нет: один символ — это строка длины 1. Строки являются неизменяемыми (immutable): изменение символа “внутри” строки невозможно, создается новая строка.\n\nПримеры: `\"a\".length` и `\"a\"[0]`.\n\n```\nconst s = \"hello\";\nconsole.log(typeof s); // \"string\"\nconsole.log(s.length); // 5\nconsole.log(s[0]); // \"h\"\n\nconst t = \"h\" + \"i\";\nconsole.log(t); // \"hi\"\n```",{"id":93,"description":94,"titleAlert":19,"isTypeAlertInfo":8},"642","Работа с “символами” Unicode может быть нетривиальной: некоторые визуальные символы занимают два 16-битных элемента (суррогатные пары), поэтому `length` не всегда равен числу видимых символов.",{"id":96,"value":97,"anchor":97,"isTypeH3":8},"4396","symbol",{"id":99,"value":100,"isTypeParagraph":8},"10080","`symbol` — уникальный примитив, чаще всего применяемый как ключ свойства, чтобы избежать конфликтов имен. Символы уникальны даже при одинаковом описании.\n\nПримеры: `Symbol(\"id\")` и `sym1 === sym2`.\n\n```\nconst sym1 = Symbol(\"id\");\nconst sym2 = Symbol(\"id\");\n\nconsole.log(typeof sym1); // \"symbol\"\nconsole.log(sym1 === sym2); // false\n\nconst user = {\n name: \"Ann\",\n [sym1]: 123\n};\n\nconsole.log(user.name); // \"Ann\"\nconsole.log(user[sym1]); // 123\nconsole.log(Object.keys(user)); // [\"name\"] (символьный ключ не перечисляется через keys)\n```\n\nСуществует глобальный реестр символов через `Symbol.for(\"key\")`, в котором одинаковый ключ возвращает один и тот же символ.\n\n```\nconst a = Symbol.for(\"shared\");\nconst b = Symbol.for(\"shared\");\nconsole.log(a === b); // true\n```",{"id":102,"value":103,"anchor":103,"isTypeH3":8},"4397","object",{"id":105,"value":106,"isTypeParagraph":8},"10081","`object` — непримитивный тип: значения имеют идентичность (ссылку), свойства и прототип. Сюда относятся обычные объекты, массивы, функции, даты, коллекции и пользовательские экземпляры классов.\n\nПримеры: `typeof {}` и `Array.isArray([])`.\n\n```\nconst obj = { a: 1 };\nconst arr = [1, 2, 3];\nfunction fn() {}\n\nconsole.log(typeof obj); // \"object\"\nconsole.log(typeof arr); // \"object\"\nconsole.log(typeof fn); // \"function\"\n\nconsole.log(Array.isArray(arr)); // true\nconsole.log(arr instanceof Array); // true\n```\n\nКлючевая особенность объектов — сравнение по ссылке, а не по содержимому.\n\n```\nconst a = { x: 1 };\nconst b = { x: 1 };\nconst c = a;\n\nconsole.log(a === b); // false (разные объекты)\nconsole.log(a === c); // true (одна и та же ссылка)\n```",{"id":108,"value":109,"anchor":110,"isTypeH2":8},"4379","Важные проверки типов на практике","practical-type-checking",{"id":112,"value":113,"isTypeParagraph":8},"10082","Оператор `typeof` полезен, но имеет нюансы. Для надежных проверок обычно комбинируются разные техники.\n\n```\n// typeof для примитивов\nconsole.log(typeof undefined); // \"undefined\"\nconsole.log(typeof null); // \"object\" (нюанс)\nconsole.log(typeof true); // \"boolean\"\nconsole.log(typeof 1); // \"number\"\nconsole.log(typeof 1n); // \"bigint\"\nconsole.log(typeof \"x\"); // \"string\"\nconsole.log(typeof Symbol()); // \"symbol\"\n\n// typeof для объектов\nconsole.log(typeof {}); // \"object\"\nconsole.log(typeof []); // \"object\"\nconsole.log(typeof (() => {})); // \"function\"\n```\n\nДля различения “обычный объект vs массив vs дата” часто применяются:\n\n- `Array.isArray(value)` для массивов\n- `value instanceof Date` для дат (в рамках одного глобального контекста)\n- `Object.prototype.toString.call(value)` как более универсальный способ\n\n```\nfunction tagOf(v) {\n return Object.prototype.toString.call(v);\n}\n\nconsole.log(tagOf([])); // \"[object Array]\"\nconsole.log(tagOf({})); // \"[object Object]\"\nconsole.log(tagOf(new Date())); // \"[object Date]\"\nconsole.log(tagOf(null)); // \"[object Null]\"\nconsole.log(tagOf(undefined)); // \"[object Undefined]\"\n```",{"id":115,"value":116,"anchor":117,"isTypeH2":8},"4380","Примитивы vs объекты: копирование и изменение","primitives-vs-objects-copying",{"id":119,"value":120,"isTypeParagraph":8},"10083","Примитивные значения копируются “как значение”, а объекты передаются как ссылка на один и тот же объект. Это особенно важно при присваивании и передаче в функции.\n\n```\n// Примитив: копия значения\nlet a = 10;\nlet b = a;\nb = 20;\n\nconsole.log(a); // 10\nconsole.log(b); // 20\n\n// Объект: копия ссылки\nlet o1 = { count: 1 };\nlet o2 = o1;\no2.count = 2;\n\nconsole.log(o1.count); // 2\nconsole.log(o2.count); // 2\n```\n\nЧтобы получить “поверхностную” копию объекта, часто используется `structuredClone` (глубокая копия, где поддерживается) или комбинации вроде `Object.assign`/spread для поверхностной копии.",{"id":122,"description":123,"titleAlert":19,"isTypeAlertWarning":8},"702","Поверхностная копия не копирует вложенные объекты: вложенные ссылки остаются общими.",{"id":125,"value":126,"isTypeParagraph":8},"10084","```\nconst original = { inner: { x: 1 } };\nconst shallow = { ...original };\n\nshallow.inner.x = 999;\n\nconsole.log(original.inner.x); // 999 (вложенный объект общий)\n```",{"id":128,"value":129,"anchor":130,"isTypeH2":8},"4381","Частые ошибки начинающих","common-beginner-mistakes",{"id":132,"value":133,"isTypeParagraph":8},"10085","- Ожидание, что `null` даст `typeof null === \"null\"`, хотя фактически возвращается `\"object\"`\n- Попытка хранить “большие целые” в `number` без потери точности, хотя безопасный диапазон ограничен `Number.MAX_SAFE_INTEGER`\n- Смешивание `bigint` и `number` в арифметике без преобразования\n- Ожидание, что массив — отдельный тип, хотя он является объектом и проверяется через `Array.isArray`\n- Использование объектов-оберток `new Number(1)`, `new String(\"x\")`, `new Boolean(false)` вместо примитивов",{"id":135,"value":136,"isTypeParagraph":8},"10086","Кратко: В JavaScript существует 8 типов данных: 7 примитивов (`undefined`, `null`, `boolean`, `number`, `bigint`, `string`, `symbol`) и 1 непримитивный (`object`). Массивы и функции относятся к `object` (функции имеют `typeof === \"function\"`), а `typeof null` — историческое исключение, возвращающее `\"object\"`.",{"id":138,"options":139,"hint":174,"solution":175,"description":7},"1146",[140,143,146,150,153,156,159,162,165,168,171],{"id":141,"label":142,"isCorrect":8},"4722","`undefined`",{"id":144,"label":145,"isCorrect":8},"4723","`null`",{"id":147,"label":148,"isCorrect":149},"4724","`array`",false,{"id":151,"label":152,"isCorrect":8},"4725","`boolean`",{"id":154,"label":155,"isCorrect":8},"4726","`number`",{"id":157,"label":158,"isCorrect":8},"4727","`bigint`",{"id":160,"label":161,"isCorrect":149},"4728","`float`",{"id":163,"label":164,"isCorrect":8},"4729","`string`",{"id":166,"label":167,"isCorrect":8},"4730","`symbol`",{"id":169,"label":170,"isCorrect":8},"4731","`object`",{"id":172,"label":173,"isCorrect":149},"4732","`character`","Следует запомнить, что в JavaScript существует 7 примитивных типов плюс 1 непримитивный (`object`): всего 8. \nУдобная проверка — перечисление того, что возвращает `typeof` для значений, с отдельным запоминанием исключения `null`.","Правильные ответы:\n\n- `undefined`\n- `null`\n- `boolean`\n- `number`\n- `bigint`\n- `string`\n- `symbol`\n- `object`\n\nНеправильные ответы:\n\n- `array` — массивы не являются отдельным типом верхнего уровня, это частный случай `object`\n- `float` — отдельного типа для чисел с плавающей точкой нет, используется `number`\n- `character` — отдельного символьного типа нет, одиночный символ хранится в `string`","quizQuestion",{"title":7,"description":178,"ogTitle":179,"ogDescription":178,"ogImageUrl":180,"canonical":19,"ogLocale":181,"ogSiteName":182,"ogImageType":183,"ogImageWidth":184,"ogImageHeight":185,"ogType":186,"ogUrl":19},"Полный список типов JS, отличия примитивов от объектов, typeof, примеры и частые ошибки для начинающих.","Типы данных в JavaScript: примитивы и объекты","/og-image.png","ru_RU","goodwebjob.ru","image_jpeg","1200","630","article",{"siteName":188,"siteUrl":189},"GOOD WEB JOB!","https://goodwebjob.ru",[191],{"label":192,"slug":193,"to":194},"Подготовка к тех.интервью","technical-interview","/technical-interview/where-to-begin",{"navigationList":196,"navigationSublist":204},[197,200],{"path":194,"isActive":149,"name":198,"icon":199,"isNavbarMobileDisabled":8},"С чего начать?","material-symbols:visibility-outline-rounded",{"path":201,"isActive":8,"name":202,"icon":203,"isNavbarMobileDisabled":149},"/technical-interview/tasks","Сборник задач","material-symbols:task-outline",[205,214,241,253,259,399,423,432,438,501,522,528],{"title":206,"list":207,"isOpened":149},"Bash",[208,211],{"name":209,"path":210,"isActive":149},"Дан фрагмент bash-скрипта: cd ~; mkdir foo... Что в нем происходит?","/technical-interview/tasks/here-is-a-fragment-of-a-bash-script-cd-mkdir-foo-what-is-happening-in-this-script",{"name":212,"path":213,"isActive":149},"Дан фрагмент bash-скрипта: target=$(ps -Af | grep $1 | head -n 1)...","/technical-interview/tasks/here-is-a-fragment-of-a-bash-script-target-ps-af-grep-1-head-n-1",{"title":215,"list":216,"isOpened":149},"CSS",[217,220,223,226,229,232,235,238],{"name":218,"path":219,"isActive":149},"Дан HTML-код. Какой будет цвет у текста «Some dummy text»?","/technical-interview/tasks/the-html-code-is-given-what-will-be-the-color-of-the-some-dummy-text",{"name":221,"path":222,"isActive":149},"Есть шаблон HTML и CSS кода. Какой будет цвет у текста «Таким образом, постоянное»?","/technical-interview/tasks/there-is-a-template-for-html-and-css-code-what-color-will-the-text-thus-constant-have",{"name":224,"path":225,"isActive":149},"Есть шаблон вложенного HTML кода. Какой будет цвет у текста «One more dummy text»?","/technical-interview/tasks/there-is-a-template-for-embedded-html-code-what-will-be-the-color-of-the-one-more-dummy-text",{"name":227,"path":228,"isActive":149},"Есть шаблон вложенного HTML кода. Будет ли display:block у body влиять на span?","/technical-interview/tasks/there-is-a-template-for-embedded-html-code-will-there-be-a-display-does-bodys-block-affect-span",{"name":230,"path":231,"isActive":149},"Есть HTML код. Будет ли font-weight на span влиять?","/technical-interview/tasks/there-is-an-html-code-will-font-weight-affect-span",{"name":233,"path":234,"isActive":149},"Flexbox и Grid, чем отличаются друг от друга?","/technical-interview/tasks/what-are-the-differences-between-flexbox-and-grid",{"name":236,"path":237,"isActive":149},"Заменяют ли Flexbox и Grid друг друга?","/technical-interview/tasks/do-flexbox-and-grid-replace-each-other",{"name":239,"path":240,"isActive":149},"Есть CSS и JS анимация. Какая между ними разница, что быстрее, что более удобно?","/technical-interview/tasks/there-are-css-and-js-animations-what-is-the-difference-between-them-and-which-is-faster-and-more-convenient",{"title":242,"list":243,"isOpened":149},"Git",[244,247,250],{"name":245,"path":246,"isActive":149},"Разрабатывал, взял закоммитил, запушил. Оказалось, что запушил не в ту ветку, точнее, коммит не в ту ветку. Какие действия?","/technical-interview/tasks/developed-it-committed-it-and-launched-it-it-turned-out-that-i-had-pushed-it-to-the-wrong-branch-or-rather-the-commit-was-in-the-wrong-branch-what-actions",{"name":248,"path":249,"isActive":149},"В git есть несколько вариантов слияния веток, какие? Чем отличаются?","/technical-interview/tasks/git-has-several-options-for-merging-branches-which-ones-how-are-they-different",{"name":251,"path":252,"isActive":149},"Какие существуют стратегии ветвления для работы команды? Что это такое?","/technical-interview/tasks/what-are-the-branching-strategies-for-the-team-what-is-it",{"title":254,"list":255,"isOpened":149},"HTML",[256],{"name":257,"path":258,"isActive":149},"Что такое HTML?","/technical-interview/tasks/what-is-html",{"title":260,"list":261,"isOpened":149},"JavaScript",[262,265,268,271,274,277,280,283,286,289,292,295,298,301,304,307,310,313,316,319,321,324,327,330,333,336,339,342,345,348,351,354,357,360,363,366,369,372,375,378,381,384,387,390,393,396],{"name":263,"path":264,"isActive":149},"Какие логические значения в console.log будут получены?","/technical-interview/tasks/prototype-what-logical-values-will-be-received-in-console-log",{"name":266,"path":267,"isActive":149},"Почему опасно писать прямо в прототипы базовых типов?","/technical-interview/tasks/why-is-it-dangerous-to-write-directly-to-the-prototypes-of-basic-types",{"name":269,"path":270,"isActive":149},"Что вернёт следующий код? Object.create(null).hasOwnProperty('toString')","/technical-interview/tasks/what-will-the-following-code-return-object-create-null-has-own-property-to-string",{"name":272,"path":273,"isActive":149},"Какое значение выведет консоль с object.property?","/technical-interview/tasks/what-value-will-the-console-output-with-object-property",{"name":275,"path":276,"isActive":149},"Что выведется в console.log([arr[0](), arr[0]()])?","/technical-interview/tasks/what-will-be-displayed-in-console-log-arr-0-arr-0",{"name":278,"path":279,"isActive":149},"Что выведет console.log в результате выполнения цикла while?","/technical-interview/tasks/what-will-console-log-output-as-a-result-of-executing-the-while-loop",{"name":281,"path":282,"isActive":149},"Есть функция и объект. Напишите все известные вам способы, чтобы вывести в консоли значение x из объекта, используя функцию","/technical-interview/tasks/there-is-a-function-and-an-object-write-all-the-ways-you-know-to-output-the-value-of-x-from-an-object-in-the-console-using-the-function",{"name":284,"path":285,"isActive":149},"Что вернёт метод book.getUpperName()?","/technical-interview/tasks/what-will-the-book-get-upper-name-method-return",{"name":287,"path":288,"isActive":149},"Переменные объявлены следующим образом: a=3; b=«hello»;. Укажите правильное утверждение","/technical-interview/tasks/variables-are-declared-as-follows-specify-the-correct-statement",{"name":290,"path":291,"isActive":149},"Что выведет консоль в случае присвоения свойства массиву по строковому положительному индексу?","/technical-interview/tasks/what-will-the-console-display-if-a-property-is-assigned-to-an-array-using-a-positive-string-index",{"name":293,"path":294,"isActive":149},"Что выведет консоль в случае присвоения свойства массиву по строковому отрицательному индексу?","/technical-interview/tasks/what-will-the-console-display-if-a-property-is-assigned-to-an-array-using-a-negative-string-index",{"name":296,"path":297,"isActive":149},"Что выведет консоль в случае удаления элемента массива с помощью оператора delete?","/technical-interview/tasks/what-will-the-console-output-if-an-array-element-is-deleted-using-the-delete-operator",{"name":299,"path":300,"isActive":149},"Что вернёт этот код: typeof (function(){})()","/technical-interview/tasks/what-this-code-will-return-typeof-function",{"name":302,"path":303,"isActive":149},"Что получится в результате передачи объекта как аргумента в функцию и выполнения кода?","/technical-interview/tasks/what-will-happen-when-an-object-is-passed-as-an-argument-to-a-function-and-the-code-is-executed",{"name":305,"path":306,"isActive":149},"Какие способы объявления функции есть в JavaScript?","/technical-interview/tasks/what-are-the-ways-to-declare-a-function-in-javascript",{"name":308,"path":309,"isActive":149},"Что такое this в JavaScript?","/technical-interview/tasks/what-is-this-in-javascript",{"name":311,"path":312,"isActive":149},"Что такое Event Loop, как работает?","/technical-interview/tasks/what-is-an-event-loop-and-how-does-it-work",{"name":314,"path":315,"isActive":149},"Что будет, если вызвать typeof на необъявленной переменной?","/technical-interview/tasks/what-happens-if-you-call-typeof-on-an-undeclared-variable",{"name":317,"path":318,"isActive":149},"Что показывает оператор typeof в JavaScript?","/technical-interview/tasks/what-does-the-typeof-operator-show-in-javascript",{"name":7,"path":320,"isActive":149},"/technical-interview/tasks/what-types-of-data-exist-in-javascript",{"name":322,"path":323,"isActive":149},"Какую структуру использовать для хранения упорядоченного списка строк в JavaScript?","/technical-interview/tasks/what-is-the-best-structure-to-use-for-storing-an-ordered-list-of-strings-in-javascript",{"name":325,"path":326,"isActive":149},"Что вернет typeof для массива?","/technical-interview/tasks/what-will-typeof-return-for-an-array",{"name":328,"path":329,"isActive":149},"Почему оператор typeof, применённый к массиву, возвращает объект?","/technical-interview/tasks/why-does-the-typeof-operator-applied-to-an-array-return-an-object",{"name":331,"path":332,"isActive":149},"Если нужно хранить список уникальных строк, какую структуру данных выбрать?","/technical-interview/tasks/if-you-need-to-store-a-list-of-unique-strings-which-data-structure-should-i-choose",{"name":334,"path":335,"isActive":149},"Что возвращает typeof для new Set в JavaScript?","/technical-interview/tasks/what-does-typeof-return-for-new-set-in-javascript",{"name":337,"path":338,"isActive":149},"Почему в JavaScript два объекта с одинаковым содержимым при сравнении возвращают false?","/technical-interview/tasks/why-do-two-objects-with-the-same-content-return-false-when-compared-in-javascript",{"name":340,"path":341,"isActive":149},"В чем разница между микро- и макро-тасками в JavaScript?","/technical-interview/tasks/what-is-the-difference-between-micro-and-macro-tasks-in-javascript",{"name":343,"path":344,"isActive":149},"arr.push(0) повлияет на массив так же, как если бы мы выполнили...","/technical-interview/tasks/arr-push-0-will-affect-the-array-in-the-same-way-as-if-we-performed",{"name":346,"path":347,"isActive":149},"Вернуть массив от 1 до n, где числа, кратные 3, заменены на 'fizz', кратные 5 - на 'buzz', а кратные и 3, и 5 одновременно - на 'fizzbuzz'","/technical-interview/tasks/returns-an-array-from-1-to-n-replacing-numbers-that-are-multiples-of-3-with-fizz-numbers-that-are-multiples-of-5-with-buzz-and-numbers-that-are-multiples-of-both-3-and-5-with-fizzbuzz",{"name":349,"path":350,"isActive":149},"Дана строка: 'one.two.three.four.five'. Необходимо из строки сделать вложенный объект","/technical-interview/tasks/the-string-one-two-three-four-five-is-given-it-is-necessary-to-make-a-nested-object-out-of-the-string",{"name":352,"path":353,"isActive":149},"Дано дерево (вложенный объект), надо найти сумму всех вершин","/technical-interview/tasks/given-a-tree-nested-object-it-is-necessary-to-find-the-sum-of-all-vertices",{"name":355,"path":356,"isActive":149},"Для каждого вложенного объекта нужно добавить свойство level, которое равняется числу - номер вложенности","/technical-interview/tasks/for-each-nested-object-you-need-to-add-the-level-property-which-is-equal-to-a-number-the-nesting-number",{"name":358,"path":359,"isActive":149},"Для каждой ветви дерева записать номер вложенности данной ветви","/technical-interview/tasks/for-each-branch-of-the-tree-write-down-the-nesting-number-of-this-branch",{"name":361,"path":362,"isActive":149},"Есть массив, в котором лежат объекты с датами, необходимо отсортировать даты по возрастанию","/technical-interview/tasks/there-is-an-array-containing-objects-with-dates-that-need-to-be-sorted-by-date",{"name":364,"path":365,"isActive":149},"Есть слова в массиве, необходимо определить, состоят ли они из одних и тех же букв","/technical-interview/tasks/there-are-words-in-the-array-it-is-necessary-to-determine-whether-they-consist-of-the-same-letters",{"name":367,"path":368,"isActive":149},"Есть строка, состоящая из разных скобок, необходимо проверить, закрыты ли все","/technical-interview/tasks/there-is-a-string-consisting-of-different-brackets-it-is-necessary-to-check-whether-all-are-closed",{"name":370,"path":371,"isActive":149}," Найти в массиве неповторяющиеся числа","/technical-interview/tasks/find-non-repeating-numbers-in-an-array",{"name":373,"path":374,"isActive":149},"Напишите функцию, который сделает из массива объект","/technical-interview/tasks/write-a-function-that-will-make-an-object-out-of-an-array",{"name":376,"path":377,"isActive":149},"Необходимо проверить, являются ли две строки анаграммами друг друга","/technical-interview/tasks/checks-whether-two-strings-are-anagrams-of-each-other",{"name":379,"path":380,"isActive":149},"Нечётные числа должны отсортироваться по возрастанию, а чётные должны остаться на своих местах","/technical-interview/tasks/odd-numbers-should-be-sorted-in-ascending-order-and-even-numbers-should-remain-in-their-original-positions",{"name":382,"path":383,"isActive":149},"Определить, является ли слово палиндромом","/technical-interview/tasks/determines-whether-a-word-is-a-palindrome",{"name":385,"path":386,"isActive":149},"«Расплющивание» массива","/technical-interview/tasks/flattening-the-array",{"name":388,"path":389,"isActive":149},"Реализовать функцию, принимающую аргументы \"*\", \"1\", \"b\", \"1c\" и возвращающую строку \"1*b*1c\"","/technical-interview/tasks/implement-a-function-that-accepts-arguments-1-b-1c-and-the-return-string-1-b-1c",{"name":391,"path":392,"isActive":149},"Сжатие строк","/technical-interview/tasks/string-compression",{"name":394,"path":395,"isActive":149},"Уникализация значений в массиве","/technical-interview/tasks/unifying-values-in-an-array",{"name":397,"path":398,"isActive":149},"Числа от 1 до 100 находятся в массиве, они хаотично перемешанные, но в нём не хватает одного числа из этой последовательности. Необходимо найти его","/technical-interview/tasks/the-numbers-from-1-to-100-are-in-the-array-they-are-randomly-mixed-but-it-lacks-one-number-from-this-sequence-it-is-necessary-to-find-him",{"title":400,"list":401,"isOpened":149},"React",[402,405,408,411,414,417,420],{"name":403,"path":404,"isActive":149},"Для чего нужен React, какие он решает проблемы?","/technical-interview/tasks/what-is-react-used-for-and-what-problems-does-it-solve",{"name":406,"path":407,"isActive":149},"Какой механизм лежит в основе оптимизации обновлений DOM в React?","/technical-interview/tasks/what-is-the-underlying-mechanism-for-optimizing-dom-updates-in-react",{"name":409,"path":410,"isActive":149},"Если убрать в React VDOM/Fiber, и вручную изменять DOM, разве это не оптимально?","/technical-interview/tasks/if-you-remove-the-vdom-fiber-in-react-and-manually-change-the-dom-isn-t-that-optimal",{"name":412,"path":413,"isActive":149},"Есть блок кода. Что в реальном DOM изменится после нажатия на кнопку?","/technical-interview/tasks/there-is-a-block-of-code-what-changes-in-the-real-dom-after-clicking-the-button",{"name":415,"path":416,"isActive":149},"Есть код, в котором список и кнопка. Что в реальном DOM изменится после нажатия на кнопку?","/technical-interview/tasks/there-is-a-code-in-which-there-is-a-list-and-a-button-what-will-change-in-the-real-dom-after-clicking-on-the-button",{"name":418,"path":419,"isActive":149},"Зачем нужен Redux (Mobx/Effector)? Зачем нужен менеджер состояния? Какие проблемы решает?","/technical-interview/tasks/why-do-we-need-redux-mobx-effector-why-do-we-need-a-state-manager-what-problems-does-it-solve",{"name":421,"path":422,"isActive":149},"Что мешает организовать централизованное состояние без менеджера состояния? Если организовать состояние механизмами реакта: контекстом, стейтом, в чем проблема? Что менеджеры состояния привносят?","/technical-interview/tasks/what-prevents-you-from-organizing-a-centralized-state-without-a-state-manager-if-you-organize-the-state-using-react-context-and-state-mechanisms-what-is-the-problem-what-do-state-managers-add",{"title":424,"list":425,"isOpened":149},"Алгоритмы",[426,429],{"name":427,"path":428,"isActive":149},"Что такое алгоритмическая сложность?","/technical-interview/tasks/what-is-algorithmic-complexity",{"name":430,"path":431,"isActive":149},"Какая алгоритмическая сложность у \"быстрой сортировки\"?","/technical-interview/tasks/what-is-the-algorithmic-complexity-of-quick-sort",{"title":433,"list":434,"isOpened":149},"Дебаггинг",[435],{"name":436,"path":437,"isActive":149},"Как диагностировать и исправить нежелательное изменение цвета фона по клику на кнопку, если исходный код сайта запутан и недоступен для прямого чтения?","/technical-interview/tasks/how-can-diagnose-and-fix-unwanted-background-color-changes-when-clicking-on-a-button-if-the-source-code-of-the-site-is-confusing-and-inaccessible-to-direct-reading",{"title":439,"list":440,"isOpened":149},"Компьютерные сети",[441,444,447,450,453,456,459,462,465,468,471,474,477,480,483,486,489,492,495,498],{"name":442,"path":443,"isActive":149},"Как браузер после ввода домена понимает, откуда брать сайт?","/technical-interview/tasks/how-does-the-browser-know-where-to-get-the-website-after-entering-the-domain",{"name":445,"path":446,"isActive":149},"Что такое DNS, как DNS находит нужный IP-адрес?","/technical-interview/tasks/what-is-dns-and-how-does-dns-find-the-correct-ip-address",{"name":448,"path":449,"isActive":149},"Как домен попадает в DNS в таблицу соответствия: домен – ip","/technical-interview/tasks/how-does-a-domain-get-into-the-dns-mapping-table-domain-ip",{"name":451,"path":452,"isActive":149},"Как браузер решает, какое соединение ему открывать, TCP или UDP?","/technical-interview/tasks/how-does-a-browser-decide-whether-to-open-a-tcp-or-udp-connection",{"name":454,"path":455,"isActive":149},"Ключевые отличия TCP и UDP","/technical-interview/tasks/key-differences-between-tcp-and-udp",{"name":457,"path":458,"isActive":149},"\"TCP/IP\" - кем является TCP, а кем IP в данном случае?","/technical-interview/tasks/tcp-ip-who-is-tcp-and-who-is-ip-in-this-case",{"name":460,"path":461,"isActive":149},"Что такое HTTP и из чего состоит?","/technical-interview/tasks/what-is-http-and-what-does-it-consist-of",{"name":463,"path":464,"isActive":149},"Что такое заголовки в HTTP и зачем они нужны?","/technical-interview/tasks/what-are-http-headers-and-why-do-we-need-them",{"name":466,"path":467,"isActive":149},"Что такое параметры в HTTP?","/technical-interview/tasks/what-are-http-parameters",{"name":469,"path":470,"isActive":149},"Где находится HTML-код в структуре HTTP-ответа?","/technical-interview/tasks/where-is-the-html-code-located-in-the-http-response-structure",{"name":472,"path":473,"isActive":149},"Чем отличаются 1.0, 1.1, 2.0, 3.0 версии HTTP?","/technical-interview/tasks/what-are-the-differences-between-http-versions-1-0-1-1-2-0-and-3-0",{"name":475,"path":476,"isActive":149},"Пользователь авторизован на сайте. Как сервер узнает об этом с последующими другими заходами, что «я – авторизованный пользователь»?","/technical-interview/tasks/the-user-is-logged-in-on-the-website-how-does-the-server-know-that-i-am-an-authorized-user-when-the-user-logs-in-again",{"name":478,"path":479,"isActive":149},"Что такое cookie?","/technical-interview/tasks/what-is-a-cookie",{"name":481,"path":482,"isActive":149},"Кто является инициатором записи cookie в браузере?","/technical-interview/tasks/who-initiates-the-cookie-recording-in-the-browser",{"name":484,"path":485,"isActive":149},"Есть ли возможность с клиента (с браузера) управлять cookie?","/technical-interview/tasks/is-it-possible-to-manage-cookies-from-the-client-browser",{"name":487,"path":488,"isActive":149},"Верно ли утверждение, что злоумышленник, контролирующий роутер и прослушивающий трафик, может получить логины и пароли от сайтов, на которые заходит клиент?","/technical-interview/tasks/is-it-true-that-an-attacker-who-controls-a-router-and-listens-to-traffic-can-obtain-logins-and-passwords-from-websites-that-a-client-visits",{"name":490,"path":491,"isActive":149},"Всё, что идет по HTTPS – оно защищено?","/technical-interview/tasks/is-everything-that-goes-through-https-secure",{"name":493,"path":494,"isActive":149},"Все данные зашифрованы, используется https. Хакер взламывает dns и делает подмену одного ip на другой, на фишинговый сайт. В этом случае, злоумышленник может получить данные (логин \\ пароль)?","/technical-interview/tasks/all-data-is-encrypted-https-is-used-let-s-assume-a-hacker-hacks-the-dns-and-makes-a-substitution-of-one-ip-for-another-a-phishing-site",{"name":496,"path":497,"isActive":149},"Есть веб-приложение. Помимо HTTP, какие протоколы того же уровня (Application Layer) можно дополнительно использовать в веб-приложении в браузере?","/technical-interview/tasks/there-is-a-web-application-in-addition-to-http-what-other-protocols-of-the-same-level-application-layer-can-be-used-in-the-web-application-in-browser",{"name":499,"path":500,"isActive":149},"Каким способом может выполняться авторизация пользователя на сайте?","/technical-interview/tasks/how-can-a-user-be-authorized-on-a-website",{"title":502,"list":503,"isOpened":149},"Отрисовка в браузере",[504,507,510,513,516,519],{"name":505,"path":506,"isActive":149},"Что происходит, когда HTTP прислал HTML? Что браузер дальше делает c HTML с учетом того, что она валидная?","/technical-interview/tasks/what-happens-when-http-sends-html-what-does-the-browser-do-with-this-html-given-that-it-is-valid",{"name":508,"path":509,"isActive":149},"Как браузер парсит JavaScript и изображения при рендеринге?","/technical-interview/tasks/how-the-browser-parses-javascript-and-images-when-rendering",{"name":511,"path":512,"isActive":149},"Что в браузере блокирует рендеринг страницы?","/technical-interview/tasks/what-is-blocking-the-page-rendering-in-the-browser",{"name":514,"path":515,"isActive":149},"Что такое DOM в браузере? Что такое CSSOM?","/technical-interview/tasks/what-is-dom-in-a-browser-what-is-cssom",{"name":517,"path":518,"isActive":149},"Что является узлами в DOM?","/technical-interview/tasks/what-are-nodes-in-the-dom",{"name":520,"path":521,"isActive":149},"Из чего состоит CSSOM?","/technical-interview/tasks/what-does-cssom-consist-of",{"title":523,"list":524,"isOpened":149},"Ревью кода",[525],{"name":526,"path":527,"isActive":149},"По каким характеристикам, ревьюер понимает, что данный код - хороший, а этот код - плохой?","/technical-interview/tasks/how-does-a-reviewer-know-which-code-is-good-and-which-code-is-bad",{"title":529,"list":530,"isOpened":149},"Теория вероятности",[531,534,537],{"name":532,"path":533,"isActive":149},"В комнате три человека. Какова вероятность того, что хотя бы двое из них одного пола? То есть два и более.","/technical-interview/tasks/there-are-three-people-in-the-room-what-is-the-probability-that-at-least-two-of-them-are-of-the-same-sex-that-is-two-or-more",{"name":535,"path":536,"isActive":149},"Есть монета. Ее подбрасывают пять раз подряд. Каждый раз записывается, что выпало - орел или решка. Сколько разных последовательностей орлов и решек может при этом получиться?","/technical-interview/tasks/there-is-a-coin-it-is-tossed-five-times-in-a-row-each-time-it-is-recorded-whether-it-lands-on-heads-or-tails-how-many-different-sequences-of-heads-and-tails-can-be-obtained",{"name":538,"path":539,"isActive":149},"Как гарантированно найти лёгкую фальшивую монету среди 8 за минимальное число взвешиваний на чашечных весах?","/technical-interview/tasks/how-can-you-guarantee-to-find-an-easy-fake-coin-among-8-in-the-minimum-number-of-weighings-on-a-balance-scale",{"slugs":541},[542,545,547,549,551,554,557,559,561,563,565,567,570,572,574,576,578,580,582,584,586,588,590,592,594,596,598,600,602,604,606,608,610,612,614,616,618,620,622,624,626,628,630,632,634,636,638,640,642,644,646,648,651,653,655,657,659,661,663,665,667,669,671,673,675,677,679,681,683,685,687,689,691,693,695,697,699,701,703,705,707,709,711,713,715,717,719,721,723,725,727,729,731,733,735,737,739,741,743,745,747,749,751,752,754,756,758,760],{"name":543,"value":544},"Теоретические 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В основе лежит формат IEEE 754 двойной точности, что объясняет ошибки округления.",{"type":788,"tag":789,"props":1806,"children":1807},{},[1808,1809,1815,1816,1822],{"type":793,"value":1565},{"type":788,"tag":802,"props":1810,"children":1812},{"className":1811},[],[1813],{"type":793,"value":1814},"Number.isNaN(NaN)",{"type":793,"value":1297},{"type":788,"tag":802,"props":1817,"children":1819},{"className":1818},[],[1820],{"type":793,"value":1821},"0.1 + 0.2",{"type":793,"value":911},{"type":788,"tag":1123,"props":1824,"children":1827},{"className":1825,"code":1826,"language":793},[1126],"console.log(typeof 123); // \"number\"\nconsole.log(typeof 3.14); // \"number\"\n\nconsole.log(0.1 + 0.2); // 0.30000000000000004\nconsole.log(Number.isNaN(NaN)); // true\nconsole.log(NaN === NaN); // false\n\nconsole.log(1 / 0); // Infinity\nconsole.log(-1 / 0); // -Infinity\nconsole.log(Object.is(-0, 0)); // false (в JS существуют +0 и -0)\n",[1828],{"type":788,"tag":802,"props":1829,"children":1830},{"__ignoreMap":1131},[1831],{"type":793,"value":1826},{"type":788,"tag":789,"props":1833,"children":1834},{},[1835,1837,1842],{"type":793,"value":1836},"Для денежных расчетов часто выбирается подход “хранить в целых минимальных единицах” (например, копейки) или использовать ",{"type":788,"tag":802,"props":1838,"children":1840},{"className":1839},[],[1841],{"type":793,"value":76},{"type":793,"value":1843}," там, где нужна целочисленная точность и нет дробной части.",{"data":1845,"body":1846},{},{"type":785,"children":1847},[1848,1879,1896],{"type":788,"tag":789,"props":1849,"children":1850},{},[1851,1856,1858,1863,1865,1870,1872,1877],{"type":788,"tag":802,"props":1852,"children":1854},{"className":1853},[],[1855],{"type":793,"value":76},{"type":793,"value":1857}," предназначен для целых чисел произвольной длины. 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",{"type":788,"tag":802,"props":1866,"children":1868},{"className":1867},[],[1869],{"type":793,"value":76},{"type":793,"value":1871}," не смешивается с ",{"type":788,"tag":802,"props":1873,"children":1875},{"className":1874},[],[1876],{"type":793,"value":70},{"type":793,"value":1878}," в арифметике без явного преобразования.",{"type":788,"tag":789,"props":1880,"children":1881},{},[1882,1883,1888,1889,1895],{"type":793,"value":1565},{"type":788,"tag":802,"props":1884,"children":1886},{"className":1885},[],[1887],{"type":793,"value":1397},{"type":793,"value":1297},{"type":788,"tag":802,"props":1890,"children":1892},{"className":1891},[],[1893],{"type":793,"value":1894},"typeof 1n",{"type":793,"value":911},{"type":788,"tag":1123,"props":1897,"children":1900},{"className":1898,"code":1899,"language":793},[1126],"const safeLimit = Number.MAX_SAFE_INTEGER; // 9007199254740991\nconsole.log(safeLimit + 1); // 9007199254740992\nconsole.log(safeLimit + 2); // 9007199254740992 (теряется точность)\n\nconst big = 9007199254740993n;\nconsole.log(big + 2n); // 9007199254740995n\nconsole.log(typeof big); // \"bigint\"\n",[1901],{"type":788,"tag":802,"props":1902,"children":1903},{"__ignoreMap":1131},[1904],{"type":793,"value":1899},{"data":1906,"body":1907},{},{"type":785,"children":1908},[1909],{"type":788,"tag":789,"props":1910,"children":1911},{},[1912,1914,1919,1920,1925],{"type":793,"value":1913},"Операции между ",{"type":788,"tag":802,"props":1915,"children":1917},{"className":1916},[],[1918],{"type":793,"value":70},{"type":793,"value":1297},{"type":788,"tag":802,"props":1921,"children":1923},{"className":1922},[],[1924],{"type":793,"value":76},{"type":793,"value":1926}," выбрасывают ошибку TypeError.",{"data":1928,"body":1929},{},{"type":785,"children":1930},[1931],{"type":788,"tag":1123,"props":1932,"children":1935},{"className":1933,"code":1934,"language":793},[1126],"const a = 10n;\nconst b = 2;\n\n// console.log(a + b); // TypeError: Cannot mix BigInt and other types\n\nconsole.log(a + BigInt(b)); // 12n\nconsole.log(Number(a) + b); // 12 (возможна потеря точности при больших значениях)\n",[1936],{"type":788,"tag":802,"props":1937,"children":1938},{"__ignoreMap":1131},[1939],{"type":793,"value":1934},{"data":1941,"body":1942},{},{"type":785,"children":1943},[1944,1954,1972],{"type":788,"tag":789,"props":1945,"children":1946},{},[1947,1952],{"type":788,"tag":802,"props":1948,"children":1950},{"className":1949},[],[1951],{"type":793,"value":88},{"type":793,"value":1953}," хранит текст. Отдельного типа “символ” нет: один символ — это строка длины 1. Строки являются неизменяемыми (immutable): изменение символа “внутри” строки невозможно, создается новая строка.",{"type":788,"tag":789,"props":1955,"children":1956},{},[1957,1958,1964,1965,1971],{"type":793,"value":1565},{"type":788,"tag":802,"props":1959,"children":1961},{"className":1960},[],[1962],{"type":793,"value":1963},"\"a\".length",{"type":793,"value":1297},{"type":788,"tag":802,"props":1966,"children":1968},{"className":1967},[],[1969],{"type":793,"value":1970},"\"a\"[0]",{"type":793,"value":911},{"type":788,"tag":1123,"props":1973,"children":1976},{"className":1974,"code":1975,"language":793},[1126],"const s = \"hello\";\nconsole.log(typeof s); // \"string\"\nconsole.log(s.length); // 5\nconsole.log(s[0]); // \"h\"\n\nconst t = \"h\" + \"i\";\nconsole.log(t); // \"hi\"\n",[1977],{"type":788,"tag":802,"props":1978,"children":1979},{"__ignoreMap":1131},[1980],{"type":793,"value":1975},{"data":1982,"body":1983},{},{"type":785,"children":1984},[1985],{"type":788,"tag":789,"props":1986,"children":1987},{},[1988,1990,1996],{"type":793,"value":1989},"Работа с “символами” Unicode может быть нетривиальной: некоторые визуальные символы занимают два 16-битных элемента (суррогатные пары), поэтому ",{"type":788,"tag":802,"props":1991,"children":1993},{"className":1992},[],[1994],{"type":793,"value":1995},"length",{"type":793,"value":1997}," не всегда равен числу видимых символов.",{"data":1999,"body":2000},{},{"type":785,"children":2001},[2002,2012,2029,2038,2051],{"type":788,"tag":789,"props":2003,"children":2004},{},[2005,2010],{"type":788,"tag":802,"props":2006,"children":2008},{"className":2007},[],[2009],{"type":793,"value":97},{"type":793,"value":2011}," — уникальный примитив, чаще всего применяемый как ключ свойства, чтобы избежать конфликтов имен. Символы уникальны даже при одинаковом описании.",{"type":788,"tag":789,"props":2013,"children":2014},{},[2015,2016,2021,2022,2028],{"type":793,"value":1565},{"type":788,"tag":802,"props":2017,"children":2019},{"className":2018},[],[2020],{"type":793,"value":1477},{"type":793,"value":1297},{"type":788,"tag":802,"props":2023,"children":2025},{"className":2024},[],[2026],{"type":793,"value":2027},"sym1 === sym2",{"type":793,"value":911},{"type":788,"tag":1123,"props":2030,"children":2033},{"className":2031,"code":2032,"language":793},[1126],"const sym1 = Symbol(\"id\");\nconst sym2 = Symbol(\"id\");\n\nconsole.log(typeof sym1); // \"symbol\"\nconsole.log(sym1 === sym2); // false\n\nconst user = {\n name: \"Ann\",\n [sym1]: 123\n};\n\nconsole.log(user.name); // \"Ann\"\nconsole.log(user[sym1]); // 123\nconsole.log(Object.keys(user)); // [\"name\"] (символьный ключ не перечисляется через keys)\n",[2034],{"type":788,"tag":802,"props":2035,"children":2036},{"__ignoreMap":1131},[2037],{"type":793,"value":2032},{"type":788,"tag":789,"props":2039,"children":2040},{},[2041,2043,2049],{"type":793,"value":2042},"Существует глобальный реестр символов через ",{"type":788,"tag":802,"props":2044,"children":2046},{"className":2045},[],[2047],{"type":793,"value":2048},"Symbol.for(\"key\")",{"type":793,"value":2050},", в котором одинаковый ключ возвращает один и тот же символ.",{"type":788,"tag":1123,"props":2052,"children":2055},{"className":2053,"code":2054,"language":793},[1126],"const a = Symbol.for(\"shared\");\nconst b = Symbol.for(\"shared\");\nconsole.log(a === b); // true\n",[2056],{"type":788,"tag":802,"props":2057,"children":2058},{"__ignoreMap":1131},[2059],{"type":793,"value":2054},{"data":2061,"body":2062},{},{"type":785,"children":2063},[2064,2074,2092,2101,2106],{"type":788,"tag":789,"props":2065,"children":2066},{},[2067,2072],{"type":788,"tag":802,"props":2068,"children":2070},{"className":2069},[],[2071],{"type":793,"value":103},{"type":793,"value":2073}," — непримитивный тип: значения имеют идентичность (ссылку), свойства и прототип. Сюда относятся обычные объекты, массивы, функции, даты, коллекции и пользовательские экземпляры классов.",{"type":788,"tag":789,"props":2075,"children":2076},{},[2077,2078,2084,2085,2091],{"type":793,"value":1565},{"type":788,"tag":802,"props":2079,"children":2081},{"className":2080},[],[2082],{"type":793,"value":2083},"typeof {}",{"type":793,"value":1297},{"type":788,"tag":802,"props":2086,"children":2088},{"className":2087},[],[2089],{"type":793,"value":2090},"Array.isArray([])",{"type":793,"value":911},{"type":788,"tag":1123,"props":2093,"children":2096},{"className":2094,"code":2095,"language":793},[1126],"const obj = { a: 1 };\nconst arr = [1, 2, 3];\nfunction fn() {}\n\nconsole.log(typeof obj); // \"object\"\nconsole.log(typeof arr); // \"object\"\nconsole.log(typeof fn); // \"function\"\n\nconsole.log(Array.isArray(arr)); // true\nconsole.log(arr instanceof Array); // true\n",[2097],{"type":788,"tag":802,"props":2098,"children":2099},{"__ignoreMap":1131},[2100],{"type":793,"value":2095},{"type":788,"tag":789,"props":2102,"children":2103},{},[2104],{"type":793,"value":2105},"Ключевая особенность объектов — сравнение по ссылке, а не по содержимому.",{"type":788,"tag":1123,"props":2107,"children":2110},{"className":2108,"code":2109,"language":793},[1126],"const a = { x: 1 };\nconst b = { x: 1 };\nconst c = a;\n\nconsole.log(a === b); // false (разные объекты)\nconsole.log(a === c); // true (одна и та же ссылка)\n",[2111],{"type":788,"tag":802,"props":2112,"children":2113},{"__ignoreMap":1131},[2114],{"type":793,"value":2109},{"data":2116,"body":2117},{},{"type":785,"children":2118},[2119,2131,2140,2145,2181],{"type":788,"tag":789,"props":2120,"children":2121},{},[2122,2124,2129],{"type":793,"value":2123},"Оператор ",{"type":788,"tag":802,"props":2125,"children":2127},{"className":2126},[],[2128],{"type":793,"value":902},{"type":793,"value":2130}," полезен, но имеет нюансы. Для надежных проверок обычно комбинируются разные техники.",{"type":788,"tag":1123,"props":2132,"children":2135},{"className":2133,"code":2134,"language":793},[1126],"// typeof для примитивов\nconsole.log(typeof undefined); // \"undefined\"\nconsole.log(typeof null); // \"object\" (нюанс)\nconsole.log(typeof true); // \"boolean\"\nconsole.log(typeof 1); // \"number\"\nconsole.log(typeof 1n); // \"bigint\"\nconsole.log(typeof \"x\"); // \"string\"\nconsole.log(typeof Symbol()); // \"symbol\"\n\n// typeof для объектов\nconsole.log(typeof {}); // \"object\"\nconsole.log(typeof []); // \"object\"\nconsole.log(typeof (() => {})); // \"function\"\n",[2136],{"type":788,"tag":802,"props":2137,"children":2138},{"__ignoreMap":1131},[2139],{"type":793,"value":2134},{"type":788,"tag":789,"props":2141,"children":2142},{},[2143],{"type":793,"value":2144},"Для различения “обычный объект vs массив vs дата” часто применяются:",{"type":788,"tag":922,"props":2146,"children":2147},{},[2148,2159,2170],{"type":788,"tag":926,"props":2149,"children":2150},{},[2151,2157],{"type":788,"tag":802,"props":2152,"children":2154},{"className":2153},[],[2155],{"type":793,"value":2156},"Array.isArray(value)",{"type":793,"value":2158}," для массивов",{"type":788,"tag":926,"props":2160,"children":2161},{},[2162,2168],{"type":788,"tag":802,"props":2163,"children":2165},{"className":2164},[],[2166],{"type":793,"value":2167},"value instanceof Date",{"type":793,"value":2169}," для дат (в рамках одного глобального контекста)",{"type":788,"tag":926,"props":2171,"children":2172},{},[2173,2179],{"type":788,"tag":802,"props":2174,"children":2176},{"className":2175},[],[2177],{"type":793,"value":2178},"Object.prototype.toString.call(value)",{"type":793,"value":2180}," как более универсальный способ",{"type":788,"tag":1123,"props":2182,"children":2185},{"className":2183,"code":2184,"language":793},[1126],"function tagOf(v) {\n return Object.prototype.toString.call(v);\n}\n\nconsole.log(tagOf([])); // \"[object Array]\"\nconsole.log(tagOf({})); // \"[object Object]\"\nconsole.log(tagOf(new Date())); // \"[object Date]\"\nconsole.log(tagOf(null)); // \"[object Null]\"\nconsole.log(tagOf(undefined)); // \"[object Undefined]\"\n",[2186],{"type":788,"tag":802,"props":2187,"children":2188},{"__ignoreMap":1131},[2189],{"type":793,"value":2184},{"data":2191,"body":2192},{},{"type":785,"children":2193},[2194,2199,2208],{"type":788,"tag":789,"props":2195,"children":2196},{},[2197],{"type":793,"value":2198},"Примитивные значения копируются “как значение”, а объекты передаются как ссылка на один и тот же объект. 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